Electroacupuncture promotes synaptic plasticity in rats with chronic inflammatory pain-related depression by upregulating BDNF/TrkB/CREB signaling pathway.

BACKGROUND: Chronic inflammatory pain (CIP) frequently coincides with depression among patients. The onset and development of pain and depression are associated with altered neural synaptic plasticity. Electroacupuncture (EA) can effectively relieve CIP and depression. However, the underlying mechanisms have not been fully illustrated. OBJECTIVE: To explore whether EA can relieve CIP and depression by regulating hippocampal synaptic plasticity, and the present study offers foundational evidence for the efficacy of EA in treating CIP-related depression (CIPD). METHODS: Rats were divided into four groups: 0.9% normal saline group, complete Freund's adjuvant (CFA) group, CFA + duloxetine group, and CFA + EA group. Pain hypersensitivity was detected by mechanical withdrawal threshold and thermal paw withdrawal latency, and the depression level was gauged using the open field test, the sucrose preference test, and the forced swimming test. The morphology of the hippocampal neurons was observed using Nissl staining. The protein expression levels of synuclein (Syn), postsynaptic density protein-95 (PSD-95), brain-derived neurotrophic factors (BDNFs), tyrosine-protein kinase B (TrKB), p-TrkB, cAMP response element binding protein (CREB), and p-CREB were measured by western blotting and immunofluorescence staining. BDNF and TrkB mRNA expression were detected using quantitative real-time polymerase chain reaction (PCR) (qRT-PCR). The content of 5-hydroxytryptamine (5-HT) and γ-aminobutyric acid (GABA) was detected using enzyme-linked immunosorbent assay, and the glutamic acid (Glu) content was determined using the ultraviolet colorimetry method. The hippocampal neuron ultrastructure was observed using transmission electron microscopy. RESULTS: EA could alleviate CIP and related depressive behaviors as well as protect the hippocampal neuronal structure from damage and regulate 5-HT/GABA/Glu levels in the hippocampus. Additionally, EA could significantly increase the expression of synapse-associated proteins such as PSD-95 and Syn by activating the BDNF/TrKB/CREB signaling pathway. CONCLUSION: EA improves pain and depressive behaviors in CIPD rats, and the mechanism may be related to synaptic plasticity mediated by the BDNF/TrKB/CREB signaling pathway.

Dabuyuan Jian Improves Hippocampal Synaptic Plasticity of APP/PS1 Double Transgenic Mice by Regulating BDNF/TrkB/CREB Signal Pathway / 中国实验方剂学杂志

Objective:To observe the effect of Dabuyuan Jian on the synaptic plasticity of hippocampus and the brain derived neurotrophic factor （BDNF）/tyrosine kinase receptor （TrkB）/cyclic adenosine phosphate reactive element binding protein （CREB） signaling pathway in amyloid precursor protein/presenilil （APP/PS1） mice， and to explore its possible mechanism for improving synaptic plasticity. Method:Totally 36 APP/PS1 mice were divided into model group， donepezil group（6.5×10-4 g·kg-1·d-1） and Dabuyuan Jian group （13.2 g·kg-1·d-1）， and another wild mice were set as control group. The mice in control group and model group received an equal volume of saline， and the mice in each group received drugs by gavage for 30 days. The learning ability and memory of mice in each group were detected by Morris water maze. The pathological changes of neurons and synapses in the hippocampus of each group were observed by Nissl staining and Golgi staining. The expression levels of postsynaptic density protein 95 （PSD95） and synaptophysin （SYN） in hippocampus of each group were detected by immunofluorescence （IF）. The protein expression levels of BDNF， TrkB， CREB and phosphorylated CREB （p-CREB） in hippocampus were detected by Western blot. Result:As compared with the control group， the platform latency and total swimming distance of the model group were increased in the model group （P<0.01）， with decreased times of crossing the platform and staying time in the target quadrant （P<0.01）， the intracellular Nissl bodies of neurons in hippocampal CA3 area decreased or disappeared in model group， with decreased number of neurons and dendritic branches and decreased density of dendritic spine in hippocampal CA3 area of the mice （P<0.01）， and the protein expression levels of SYN， PSD95， BDNF， TrkB and p-CREB in hippocampus of mice were also decreased in model group （P<0.05， P<0.01）. As compared with the model group， the platform latency and total swimming distance were decreased in the donepezil group and Dabuyuan Jian group （P<0.05， P<0.01）， with increased times of crossing platform and staying time in target quadrant （P<0.05， P<0.01）， the number of Nissl bodies of neurons in hippocampal CA3 area was increased in the donepezil group and Dabuyuan Jian group， with increased number of neurons and dendritic branches and increased density of dendritic spine in hippocampal CA3 area of the mice， and the protein expression levels of SYN， PSD95， BDNF， TrkB and p-CREB in hippocampus of mice were increased in the donepezil group and Dabuyuan Jian group （P<0.05， P<0.01）. Conclusion:Dabuyuan Jian can improve the synaptic plasticity of APP/PS1 double transgenic mice， and its mechanism may be related to its up-regulation of BDNF/TrkB/CREB signal pathway in mouse hippocampus.

Ameliorative Effects of α-Tocopherol and/or Coenzyme Q10 on Phenytoin-Induced Cognitive Impairment in Rats: Role of VEGF and BDNF-TrkB-CREB Pathway.

Phenytoin is one of the most well-known antiepileptic drugs that cause cognitive impairment which is closely related to cAMP response element-binding protein (CREB) brain-derived neurotrophic factor (BDNF) signaling pathway. Moreover, vascular endothelial growth factor (VEGF), an endothelial growth factor, has a documented role in neurogenesis and neuronal survival and cognitive impairment. Therefore, this study aimed to investigate the influence of powerful antioxidants: α-Toc and CoQ10 alone or combined in the preservation of brain tissues and the maintenance of memory formation in phenytoin-induced cognitive impairment in rats. The following behavioral test novel object recognition and elevated plus maze were assessed after 14 days of treatment. Moreover, VEGF, BDNF, TrkB, and CREB gene expression levels in the hippocampus and prefrontal cortex were estimated using RT-PCR. Both α-Toc and CoQ10 alone or combined with phenytoin showed improvement in behavioral tests compared to phenytoin. Mechanistically, α-Toc and/or CoQ10 decreases the VEGF mRNA expression, while increases BDNF-TrKB-CREB mRNA levels in hippocampus and cortex of phenytoin-treated rats. Collectively, α-Toc and/or CoQ10 alleviated the phenytoin-induced cognitive impairment through suppressing oxidative damage. The underlying molecular mechanism of the treating compounds is related to the VEGF and enhancing BDNF-TrkB-CREB signaling pathway. Our study indicated the usefulness α-Toc or CoQ10 as an adjuvant to antiepileptic drugs with an advantage of preventing cognitive impairment and oxidative stress.

Salvianolate lyophilized injection promotes post-stroke functional recovery via the activation of VEGF and BDNF-TrkB-CREB signaling pathway.

Reports show that, while the mechanism remains unknown, salvianolate lyophilized injection (SLI) improves functional recovery after stroke in diabetic rats. In this study, we investigated the mechanism and effect of SLI on stroke outcome in type 1 diabetic (T1DM) rats. T1DM were induced in adult male Wistar rats by injecting streptozotocin. T1DM rats were then subjected to 90 minutes of middle cerebral artery occlusion (MCAO). SLI (10.5, 21, 42 mg/kg, respectively) was administered by tail vein injection at 24 hours after MCAO, and dayly and last for 14 days. The neurological deficit score and brain infarct volume were assessed after 14 days. Also, VEGF, BDNF, TrkB, CREB and p-CREB levels in the ischemic brain tissue were analyzed with western blot at 14 days after MCAO. SLI significantly reduced neurological deficit scores and cerebral infarct volume, and reduced lesion volumes at all time points. SLI also increased the expression of VEGF, BDNF, TrkB, CREB and p-CREB protein levels in T1DM-MCAO rats. In summary, our results demonstrate that SLI can improve functional recovery after stroke in diabetic rats, and the mechanism of treating cerebral ischemic injury is related to the activation of the VEGF, BDNF-TrkB-CREB signaling pathway.